/*
 * Copyright [2013-2021], Alibaba Group Holding Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.calcite.plan.volcano;

import org.apache.calcite.rel.RelNode;

/**
 * A rule driver applies rules with designed algorithms.
 */
interface RuleDriver {

    /**
     * Gets the rule queue.
     */
    RuleQueue getRuleQueue();

    /**
     * Applies rules.
     */
    void drive();

    /**
     * Callback when new RelNodes are added into RelSet.
     *
     * @param rel the new RelNode
     * @param subset subset to add
     */
    void onProduce(RelNode rel, RelSubset subset);

    /**
     * Callback when RelSets are merged.
     *
     * @param set the merged result set
     */
    void onSetMerged(RelSet set);

    /**
     * Clears this RuleDriver.
     */
    void clear();
}
